2016 – a racing review

I set this site up mainly to provide a platform to share some of my experiences and endeavours in developing the engine of my racing 1932 Scott Flying Squirrel.
The simple reason that I’ve not been updating is that I’ve not been working on my bike much or racing it either.
I did have a rather memorable meeting at Cadwell park in June, but not for the right reasons.

I have not given up on petrol or AVGAS (as I have have most recently been using) but my experiences with seizures in 2015 made me realise that I had more development work to do before I could confidently go to a racetrack again using that fuel. I have my suspicions that the diameter of either the ‘stinger’ or the muffler outlet pipe on the exhaust is inadequately sized and that excess pressure build up is creating heat at sustained higher revs. I’m not convinced that the exhaust is actually the optimum design anyway (Supposed to be a direct copy of Roger’s, but Gibsons didn’t make it with quite the same dimensions), but it certainly goes well with it on methanol and I simply didn’t have the time (or the TIG) to make test modifications at that (or this) point. However, as I’m sure I reflected on at the time, the problem may be something else entirely or indeed a combination of factors. Certainly, the seizures were not something I managed to replicate on a dyno during short output-measuring runs, although I since discovered that the dyno can indeed be set up to provide a constant load condition to replicate the conditions experienced when flat out for a period of time. It’s not really about measuring power but simply observing what is happening. To make the most of a morning on the dyno doing this, I would need to get some datalogging going to be able to really study the effect. I have thermocouple ports in the headers but I could also do with the temperature in the water jacket being monitored as well. I can switch exhausts to a standard straight-through pipe to make comparisons.The radiator is only small on my bike and may be a significant factor as well. It would likely be a couple of hundred quid for a morning on the dyno so I would have to make it count.

So, with the petrol incarnation of my engine needing time to work through the options, I thought I would return to good old methanol to give me some limited riding in 2016.
I was still hoping to try to squeeze more power out of my engine, and had the combustion chambers to my cylinder head welded up to enable a new profile to be tried. I didn’t have much time for the work on this and Roger kindly did some machining on it for me. He checked the head for flatness, which he thought was fine and I built it up.

The premise is simple. The Scott engine is limited to fairly low revs by several design constraints; you simply have to make the most out of the available range, which is effectively up to ~5000rpm (with peak torque somewhere between 3000 and 4000 rpm). I had done some development work with the cylinder head previously and seen on the dyno the effects of lowering the compression whilst improving the combustion chamber shape; I lost low rev torque whilst the engine revved to higher RPMs. If the engine was capable of breathing at higher revs, then an increase in power may have been the effect but as (according to my calculations and observations) the ports restrict the gas flow required for anything above about 3750rpm, then there’s just no point holding on.
When you also take into account the three speed box the task as I see it is to maximise low rev torque and discount the pursuit of revs entirely.

Now I would like to say at this point that a good strong engine can be made to run very reliably on petrol (of course!) and I raced it without mechanical problems for years like this (with a far less radical pipe, prior to fitting the expansion chamber I received as a wedding present from Roger!) but it is at this point where you are trying to experiment where you have to accept that you might hit trouble. I have built many engines for other people and I wouldn’t build an engine for anyone else with anything but tried and tested clearances and configurations, as we know that these work and work well but I have always wanted to keep experimenting with my own Scott engines and in doing so you commit to the highs and lows associated with that development process.

The Cadwell park meeting in June was a big event. An anniversary meeting for the British Historic Racing Club and also the Scott Owners Club, which had a stand in attendance.
The Friday had given people the opportunity to ride around the circuit on their road bikes, with a full weekends racing ahead.
I had returned to methanol for the meeting, thinking that was the safest option as I had never had problems running on methanol before. I was also quite excited at the prospect of the improvement I may find with the new cylinder head design. That excitement was short lived however as the head gasket was obviously not sealing and the water was being blown out the radiator expansion pipe.
I will not make a long story out of this weekend as it simply consisted of various attempts to seal the head (with associated peaks of hope and troughs of disappointment) aided by several kind and enthusiastic helpers. Kev Bayliss and Alan Noakes deserve a special mention.. many thanks.
Unfortunately, It was not to be. In that moment, having hired a caravan and being accompanied by my wonderful wife and two small children and being surrounded by so many Scott owners who, I’m sure, would have loved to have seen Roger and I trying our best in the vintage races, I was left with the feeling that I simply had to re-assess my approach to racing given the available time and finances available.

I never wanted to simply ride around, and when you feel like you could get more from your engine, it’s hard not to succumb to the urge to tinker. You must have the time to see it through though.

My main plan for 2017 is to finish the rebuild of my lathe and build a workshop to house my other machines; a Thiel 158 universal mill and most recently acquired, my Jones and Shipman 1014 grinder, which is a true universal toolroom machine with surface grinding, cylindrical internal and external as well as tool and cutter grinding capabilities. These are currently in storage and I need to stop playing with bikes for a while and make them a home. This has to be a priority above racing and bike development. I will rebuild the engine but I may do it as a good road engine to run with a normal pipe and finally register it for the road. I’m not certain about it, but I could possibly do some local events, hill climbs, sprints etc and enjoy it in a different way whilst building up the workshop. We’ll see but I quite like the idea. Racing is very expensive and there’s a lot of tooling I can get for the price of a two day meeting.
I have also been rebuilding a couple of engines for other people and it’s obvious that I need to have better facilities in place if I am to continue doing this within any reasonable time-frame as I’ve had to rely too heavily on Roger fitting my work into his already packed work schedule. It’s been a lesson which has contributed to my resolve that this year must be the year of the workshop.

So it may be that in 2017 my posts are less racing oriented. I’m still working on Scott engines anyway so I’ll post about that as well as my machines and any related progress.

We’ll see what happens…

Happy New Year to all who visit and good Scotting!

Back on track

I’ve been very busy but two months is a long time since the last post and I shall endeavour to do better.

One of the things that has taken a lot of my spare time in the last months has been teaching myself to draw using a 2D CAD program. I didn’t do technical drawing as an apprentice and I’ve always looked upon drawing as being such a vital skill, especially if you need to be able to get work made out by others. Of course, you can do a lot of things with a simple sketch, but it’s undoubtedly quicker and simpler (once you know how) to make changes and amendments using a digital file.
Also, where clearances are tight, and dimensions are precise, because it shows (of course) a true representation of what you are wanting to produce, it enables you to see more easily any mistakes you may have made in measurement or design. Like pretty much everything I do, 2D CAD is so old hat that on one hand it almost seems ridiculous to talk about it but it’s new to me and I think it’s the most exciting and interesting development in my education for years.

The initial incentive to push myself to learn how to use CAD was that I found myself unable to find a particular component for a Scott engine that I’ve been working on. It’s a mid twenties engine and it had a bearing cup which was both corroded and cracked. Enquiries about a replacement cup with those associated with the rebuilding of the older engines have been fruitless. However, before I go any further I should explain a little about the main bearing assembly of a Scott and why repair or replacement presents more of a challenge than for many other engines.

The Scott engine has its two crank-chambers separated by an external area which houses the central flywheel.

Inside late twenties Scott crankcase.
Inside late twenties Scott crankcase.
The crank-chambers themselves are very slim by design so as to maximise the crankcase pumping effect and so is therefore the main bearing assembly, crank assembly and big end / rod assembly. The main oil feeds are visible on the picture and are fed direct to the main bearings. These are (generally) fed by a metering unit called a Pilgrim pump (sic) which allows the user to adjust the quantity of oil delivered to each cylinder. The delivery rate in use is defined by the engine speed. The main bearings and big end bearings are roller bearing units, which involve outer and inner races that are made specifically for the Scott. Rollers themselves are fortunately still available (!) but if Scott bearings are damaged, the work to ensure the accuracy and fit of the replacement assembly requires a great deal of precise toolroom work.

A picture is worth a thousand words…

Scott main bearing bearing 'cup' in engine.
Scott main bearing bearing ‘cup’ in engine.
Scott crankcase with bearing'cup' removed
Scott crankcase with bearing’cup’ removed
Two variations of Scott main bearing cup
Two variations of Scott main bearing cup

You can see here the drilling into the outer wall of the crankcase main bearing housing

Crankcase main bearing oil feed drilling
Crankcase main bearing oil feed drilling

and you can see here the corresponding hole in the outer diameter of a main bearing cup. The groove is to give some rotational tolerance when fitting the cup.

Late Scott main bearing cup (big flange)
Late Scott main bearing cup (big flange)

Here you can see a cross sectional drawing showing the drilling through the rear of the later cup design:

Drilling detail through Scott cup
Drilling detail through Scott cup

I will one day go through the operation of the metal to metal sealing arrangement of the crank-chamber, but suffice to say that it is a spring loaded seal that in Scott circles is called a ‘gland’.

but back to the bearings.

The bearing outer is retained in the crankcase with an interference fit. This fit is necessary to provide strength to the bearing ‘cup’ during operation and to mitigate against the differential in thermal expansion between the steel cup and the aluminium crankcase. It also has to ensure the constant seal for the oil feed between the crankcase and the cup.
Even if there is no problem with the bearings themselves this interference fit diminishes over time and the cup can become less well secured. This can become evident by oil leaks noticed in the central flywheel area. Sometimes this can be oil leaking past the gland but sometimes it can be leakage at the connection of the oil feed drillings. It’s also very noticeable when you remove an old cup… often they require very little force to knock out.

The cups when newly fitted have 0.005″ interference between the outer diameter and the bore in which they fit. This means that fitting is done with a cold bearing in a hot crankcase and can be a bit ‘heart in mouth’. It is a real pain if the cup isn’t exactly square going in.

And that’s the start. You then have to make a steel ring that fits in an annular groove in the aluminium around the main bearing. This steel ring (called a shrink ring) is made to have 0.009″ interference between it’s ID and the corresponding diameter of the groove. The shrink ring is then heated until it’s red hot and dropped into position.

After all this, the mouth of the cup which is not supported in the same way as the rear, is compressed so that the bearing track is now tapered. The whole lot must be ground in situ… which is another story.

Anyway, back to my CAD drawing. I had an-usable cup and needed to have one made. Although I have some copies of Scott drawings I don’t have one for this particular component and so I thought I must make a drawing myself. After considerable efforts to get on top of the process, I am really happy with progress.

Hopefully I’ll have it finished by the end of the week.

work in progress. 1925 Scott crankcase cup drawing.
work in progress. 1925 Scott crankcase cup drawing.

Early Christmas

I’ve seen a few possibilities for purchasing potentially very useful tooling recently but for reasons of economics and priorities I’ve not been able to take them all up. One thing I did do though was to buy a number of collets specific to the Smart and Brown lathes made by Crawford collets. They are numbered 2804 and not easy to find… my lathe was probably made somewhere in the 1950’s.
Anyway, a little advance but since I am spending so much time scraping the slideways (almost 0.010″ off the second top slideway now but a lot of alignment work to go), it’s encouraging to be able to improve the possibilities of it’s usefulness when it’s finally rebuilt.

Smart and Brown '2804' collets.
Smart and Brown ‘2804’ collets.

Thinking about castings…

I went to a 3D printing show with a Scott owning friend a couple of months ago to look at the possibilities of using 3D printed models as part of the casting process for development work with Scott barrels and pistons. It was his idea, not mine but it was fascinating. There are various different possibilities: you can make a 3D CAD drawing and then print a pattern from which you then set up to produce castings in a conventional manner, you could possibly print an exact replica of the component you want out of wax or something similar and then investment cast the item such as they do with jewellery. You can also print the actual sand cores, rather than printing the patterns from which to make them. You can use a 3D scanner, either handheld or one that rotates around the component, which will interpret the image into a 3D image from which a CAD file can be automatically produced. It was very interesting, but it got me thinking about how little I really know about casting.
Roger used to have patterns made regularly, not only for his Scott but also on a far larger scale in the context of the family-run, Leicester-based special purpose machine tool company, ‘Moss Machine Tools’, that he used to be works manager/ managing director for.
That company, details of which you can find if you click the link through to ‘Moss Engineering’ at the top of this page was involved in making complex machines for automotive, MOD and other sectors from 1947 to around 1991 when economic conditions forced it to cease trading. I don’t know whether he’s ever cast anything himself but he has significant understanding through having had to work with foundrys and pattern makers and seeing the issues that have to be overcome within those areas.
I realise that I’ve been looking at all this interesting technology to possibly assist within a casting process but I still haven’t any actual experience of casting of any type. I’ve worked with castings of course, and understand a little of the some of the areas that have to be considered; shrinkage, porosity, premature cooling, incomplete filling of cores but have found myself thinking about it more and more and have gone where any self respecting modern would-be self-improver goes to nowadays… You tube.

I’ve seen several casting videos recently but here’s one that I really liked by a guy called Keith Rucker, because of the thoroughness of the explanation of the process. he’s not setting himself up as an expert but he’s doing it and seeing where it could be better. He’s also using 3D printed patterns to make vintage components! I’m not likely to be attempting to cast any time soon, but it’s all part of learning the language and gaining a better understanding at how a pattern has to be made in order to be able to make up a successful set of core boxes and ultimately a successful casting.

Scraping the night away

I’ve been trying to sort a problem out with the website which means that I can’t upload photos. Hopefully I’ll get it sorted out soon but in the meantime I’ll just have to do without.

I was brought up with Smart and Brown lathes; my dad has had a Model A for around 50 years and a 1024 VSL for around 20 years. It wasn’t therefore a huge decision what I would look for when I started to put my workshop together a few years ago. The lathe I bought (unseen off ebay) was a Model M Mk2 which was a very nice 4″ swing tool-room lathe from the late 1940’s to the end of the 1950’s.

It looks better blurred...
It looks better blurred…

It was in a pretty poor state and I think it was a long time since it was a cossetted tool-room machine. Undoubtedly shifted to some unswept corner of the maintenance shop to turn spacers on. I made several other posts about the assessment and strip-down but the most significant matter was the slide-way wear. There was 0.010″ over the length which is quite a lot!
I had wondered about grinding and looked into the costs, but it didn’t seem to be a perfect solution. True it would be a lot quicker than scraping but I could see the possibility of knock-on problems. I wanted to keep the original position of the head, which provided the correct clearance arrangements with the feed drive gears at the rear. One grinder I spoke to suggested that they had ‘shaved’ gears to get over this problem. It just didn’t seem like the right answer. Whatever I did I was going to have to re-establish the original height of the saddle once the work had been completed to ensure that the half nuts still centered on the lead-screw, the feed shaft within the apron, and the main traverse gears had the correct clearance with the rack.
So, to cut a long story short, I decided to scrape the slide-ways using a hardened rail sitting on part of the original head location face and the end of the tail-stock slide as a guide. With a clock stand moving along that whilst clocking the front way, I was not only able to see the initial wear but it gave me a basis from which I could start the work, so that I could start to scrape the worst of it out and establish a reasonable state of parallelism before moving to the next stage.
Months of intermittent scraping have followed. A bit here, a bit there. A few weeks ago, I had arrived at the point of being within 0.001″ over the slide-way according to the clock and so I went to blueing the rail and using it directly on the slide-way to establish a better flatness.
Getting there...
Getting there…
Still further hours but at last the front slide is now ‘good enough’ to sit the rail on to start to do the opposite way. There’s a lot of work to come and this is why I haven’t tried to finish the front slide perfectly. When the rear slide is done, then I’ll use a precision level on my datum faces (under the head) to set the bed horizontal and then use some ground V blocks which span the two slide-ways to establish not only the angular alignment to the head face but to ensure, using blue under the v blocks, that the alignment is achieved with faces on the same plane, not just parallel. It’s almost inevitable that after I’ve scraped the rear way, that the two faces will be parallel but not on the same plane. The process to align will mean that at least one of the ways will have to be completely re-scraped again.
Anyway, months of intermittent work ahead but the first stage is complete.

Memories of Montlery

Roger went over to the continent a number of times during the 1970’s, racing his Scott. On this early foray his Scott was pretty much as it is now, having been rebuilt by me around 10 years ago. By the late 70’s he was thick into development and had commissioned a new frame, tank and radiator and this is where his iconic current racing machine came into existence. The pictures are from Montlery, which was a great experience. One of the French racing contingent was a man called Christian Olivaux, who invited us all (the whole family went) to his apartment in Paris to stay, which we duly did on our return.
Many years have passed since this time, but my dad was sent a picture recently by Christian from Montlery in 1975. He remembers coming third in the race. Others in the picture are ( I think): Geoff Pollard (second in the race on his 1939 Tiger 100) and his son Derek (or Bill.. one was a nickname), Fred Ellis, Tim Maton (won on a Vincent twin). If anyone remembers anyone else let me know…
The picture of the group of them together is from Christian, the others are from the same meeting that Roger had already.
Happy Memories indeed.

taken from BBC news article…

A BBC article reports a court case in Australia where a two time cancer survivor, Yvonne D’Arcy, had brought a case against a US medical research company who had been awarded a patent for the BRCA1 gene after isolating it in the 1990s.

Yvonne won the case and said that she was thrilled with the verdict as it would make it easier for people to be tested for cancer risks.

Ms D’Arcy, who brought the case along with campaigning network Cancer Voices Australia, said it had been “a David and Goliath test”.

“I’m only a little person – but it’s not the size of the dog in the fight, it’s the size of the fight in the dog.”

Well said Yvonne. A quote to live by.

The complete article can be found here: http://www.bbc.co.uk/news/world-australia-34461890

August update 2015

I thought I’d better post an August update since it’s September tomorrow!

I realise that I’ve hardly been diligent in keeping up the website over the last couple of months. I’ve been so busy! I shall be better over the Autumn…

In terms of Scott activity, I’ve had more involvement with Scotts in the last few months than I’ve had for several years, since I worked with Roger rebuilding engines. I have recently started to offer my services to people who either want engine work or gearbox work, or simply want some help to try to resolve why their machine doesn’t work as they think it should. I’ve a few engines in process now and it’s a happy thing to be involved again with people who are really enthusiastic about having a good engine.

Anyway, I don’t want to say that I won’t write about work that I’m doing but I don’t want this website to change to a vehicle for my own work. If something interesting comes up, I’ll write a bit about it.

One significant Scott based event this August was the Abbotsholme weekend. I haven’t been since the first ever event, around 7 years ago I believe. Eddie Shermer and his wife Margaret have laboured to create what Roger speculated as being the ‘high water mark’ of Scott rallies. The energy and organisation to create such a successful event cannot be underestimated and I was very glad that I was able to bring my family to such a warm and welcoming event.
We were there from Friday afternoon until Sunday afternoon and stayed in our own little dormitory which was entirely comfortable and gave us the peace of mind that we had somewhere to retreat to with the children and also that any late night crying (not me) was likely to have minimal impact. My youngest is only one year old so is a bit young to require grand schemes to keep her interested. The older one, who is three, thrives on interesting adventure and activity and especially loved dancing to the excellent Ukelele band after the dinner on the Saturday night. Wonderful.
Saturday had been forecast with a downpour of such an intensity not seen since some guy was advised to fill his boat with animals. Amazingly the day was largely rain free and in fact sunny and bright for the most part. This was appreciated as it was the day for the Scott run which took in some beautiful places in Derbyshire, not least Chatsworth house which was the location for our lunch stop.
I didn’t have a bike to ride and so I gladly accepted Rogers invitation to ride ‘ballast’ in his little 500cc JZR three wheeler. Such excellent fun and we were so lucky with the weather… until about ten miles from home when the heavens opened first with a hailstorm with hailstones the size of peas and then just plain cold rain. A lot of it.
Some pictures, pre deluge, at Chatsworth.

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So we got soaked in the end. It was all part of the days entertainment and what a great entertainment it was.

Sunday was the opportunity for people to put their Scott’s out on display outside the School, and there were a few people with stands offering spare parts. Lovely to catch up with lots of people that I hadn’t seen for years and also to introduce them to my family. I think everyone seemed to be enjoying themselves and although it’s a bittersweet feeling as it’s the last one of it’s kind, I was very glad that my family participated.

July 2015 : an update

I’ve not written much recently but there’s plenty been going on.

My racer is still on the stand, although I now have a new front aluminium mudguard to replace the one damaged in the lowside crash at Anglesey earlier in the year. I also set about the paintwork on the headstock to try and find trace of a frame number, which would help me to register it for the road if I so desired. I found it in the end (but not before I’d removed a decent amount of perfectly decent paint) and amusingly it confirmed that the frame was never a Super Squirrel frame, but a 1932 Flying Squirrel. I have actually called it a Flying Squirrel in the past (and a Sprint Special when I was very young and simply wanted it to be one…) but the idea that it was a Super Squirrel stuck for some reason and I can’t even remember why. It’s not even that the engine type was the same.
So from this moment on I shall call my noble steed by its rightful title: My Flying Squirrel racer.

Although Anglesey was a while ago now, one of the other things that happened at the time was that my dad’s bike was due to be tested the following Tuesday for Classic racer magazine by Steve Plater, a former motorcycle racer and TT winner. I made the journey to Cadwell the day after getting back from Anglesey and we were very interested to see how he got on and what he made of the bike. He’s used to modern machines and I don’t think he’d ever ridden anything like it before. My dad advised caution through Charlies because of it’s tendency to get out of shape on the exit, but apart from that let him work it out himself.
We changed the bars to give him a different position and he seemed to be gaining confidence quite quickly through hall bends, where we were watching. He was certainly moving. However, maybe the confidence was a little premature as he lost it out of Charlies as a result of a tank-slapper that he couldn’t control.
Noticing that he hadn’t come round for another lap, I feared the worst and ran up to the van just in time to intercept the recovery vehicle. I took a deep breath when they opened the back door as the steel Vincent straight handlebars were bent vertically both sides, like bulls horns. I could see the top fork links had bent significantly before I even got it on the stand, and by the time Steve told me that it had gone over a couple of times I already had a mental picture of what, in all honesty, was the worst racing incident it had ever endured in over thirty years.
Of course, we were all relieved that Steve was ok. It could have been very nasty for him. On reflection, I think we were naive to think that even a highly successful professional modern rider might just sit on something with as lowly relative performance as my dad’s Scott and be able to work it out easily. Riding a rigid bike, or more to the point, racing a rigid bike requires a whole skill-set of its own. The feedback to the rider from a rigid chassis with girder (almost rigid) forks has little comparable in the modern motorcycling world. Racing with modern tyre compounds winds up the chassis and causes some instability that you get used to and some you know you can’t. Even though you ride a different line to avoid the ripples or the sudden dip in track surface etc, arse off the saddle.. damping with your knees like a jockey… there are some corners where you don’t want to try to push the line, and the exit of Charlies always has been one.
At the end of last year, Bill Swallow had a ride on my Dad’s bike in one of my races and he got into a tank-slapper coming out of Charlies which certainly caused him to wind it back it little. He knew he couldn’t push any further.
Maybe Steve felt a little under pressure to perform? Possibly, although he is obviously a great rider with a lot of experience of real racing pressure so it’s difficult to believe. I think the truth is, that he just didn’t know what the bike would do and assumed that he’d be able to tame it. It was a sad end to a day which promised some exposure for the British Historic Racing Club, plus a wonderful chance to see what a well respected modern champion might achieve with the bike in the way Paul Dobbs did with such style, ten years ago. Rest in peace, Paul.
In the end, it was a mistake, just unfortunately one which will take a while to sort out. Now stripped, his racer needs to have to frame checked for straightness, the bearings, the wheels etc. The fork blades are bent and most likely other parts of the assembly too.
Of course it will be done, but at 74 Roger has a lot of engine work for customers and it’s just difficult to find the time for minor developments, let alone complete re-alignment and rebuilding work. It won’t be done until next year, for certain. We have to remind ourselves that beyond the feelings of sadness and regret over the incident there must remain one clear point:
This is what racing is.

The virtual oily corkboard of a vintage motorcycle racing family